Continuous diazotization of amines

US4268437A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Hartmut Behringer · Nidderau, DE
• Kurt Karrenbauer · Lechenich, DE

Key dates

• Filing date: Jun 12, 1979
• Grant date: May 19, 1981
• Expiry date: Jun 12, 1999

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C245/20
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention provides a process for the continuous diazotization of primary aromatic amines by reacting an aqueous solution or suspension of the amine in a mineral acid with an aqueous sodium nitrite solution. To this end, the lower portion of a cylindrical diazotization vessel placed in upright position is fed continuously with an aqueous mineral acid solution or suspension of a diazotizable primary aromatic amine. At the same time, the vessel is fed, via one or more inlets arranged one above the other so as to open laterally thereinto, with an aqueous sodium nitrite solution, the amine and nitrite being used in stoichiometric proportions, or the nitrite being used in a stoichiometric deficiency and the acid being used in an excess of about 1 to 3 equivalents per amine equivalent in the mineral acid solution. The resulting mixture is reacted while producing a laminar flow of liquid matter at temperatures of about 5.degree. to 30.degree. C. Next, reaction mixture is removed, in accordance with the diazotization velocity of the particular amine used, from the upper portion of the diazotization vessel at a place where the reaction mixture is substantially free from nitrous acid, sai…